I used to be slower in the morning, but I eventually discovered all the tricks, cheats and hacks to make it the same. It's mostly about lights and left turns - everything I once waited for I now avoid through the use of parking lots, salmoning and generally thinking outside the box.

Don't underestimate the power of the homing instinct. Almost all people will put in more effort on the way home, without even thinking about it.

Huh? Why more effort (time?) going home? My commute runs between about 1:20-1:30. I can't tell any real difference between morning and afternoon time. Afternoon might be a tad slower because of more traffic. But unless it is really unusually bad the traffic doesn't impact my time much, which is one of the major pluses for bicycle commuting.

Weird. I'm the exact opposite, and I can feel it. I like to ride hard in the morning. In the evening, I practically coast home, or I would if I could.

It seems like I used to be faster in the afternoons, but lately my morning commutes have been faster. There are so many variables that it is hard to compare -- eg, number of traffic lights that catch you, amount of traffic, wind direction and speed, darkness or light, etc.

One thing I can say for certain is that I sweat more in the mornings. That totally baffles me because it is almost always cooler in the mornings, often by 10-20-30 degrees. I assume that it's due to higher humidity levels in mornings.